When your Mac says the disk is almost full, the quickest wins are rarely where you expect. Work through this list in order, from the safest and biggest wins to the fiddly ones.

1. See what is actually using the space

Open System Settings → General → Storage. The bar at the top splits your disk into Applications, Documents, Photos, System Data and more. Don’t delete anything yet. Just note the two or three biggest blocks, because that is where your effort should go.

2. Empty the Trash and clear Downloads

Deleted files keep taking space until the Trash is emptied. After that, open your Downloads folder and sort by size. Old disk images (.dmg), installers (.pkg) and zip files are usually the biggest and the safest to remove, because the app they installed is already on your Mac. There’s a longer walkthrough in how to clean up your Downloads folder.

3. Remove apps you no longer open

Sort Applications by size in the Storage panel and look for things you haven’t opened in months. Dragging an app to the Trash works, but it leaves files behind. See how to uninstall apps on a Mac completely.

4. Clear caches and logs

Apps keep caches in ~/Library/Caches so they can start faster. They are rebuilt on demand, so clearing them is low risk, but the gain is usually modest and the apps will be a little slower the first time you reopen them. Quit the app first. The details are in how to clear cache on a Mac.

5. Look at the invisible categories

Two things hide in plain sight:

System Data can grow to tens of gigabytes. What System Data is, and how to shrink it.
iOS backups from old iPhones and iPads live in ~/Library/Application Support/MobileSync/Backup. In Finder, select your device and choose Manage Backups to delete ones you no longer need.

6. If you write code or run local AI models

Developer machines fill up differently. Xcode build data and simulators, Docker images and local language models can each take many gigabytes. Guides for each: Xcode DerivedData and simulators, Docker and Ollama and Hugging Face models.

What to leave alone

Don’t delete anything inside /System, /Library or /private unless you know exactly what it is. Skip “RAM cleaner” and “speed up your Mac” utilities that promise miracles; macOS manages memory itself.

Doing it with less effort

Gardner is a menu-bar app that does steps 2 to 4 for you. It checks your Downloads, your apps and the clutter above, explains in plain words what each item is, and moves only what you tick to the Trash, where Restore can bring it back. It uses the Apple Intelligence model already on your Mac, so there are no AI fees.

How to free up storage on your Mac (safely)